Electric remote selective control system



May 1949- 1.. E. w. MoNTRos-osTER 7 ELECTRIC REMOTE SELECTIVE CONTROLSYSTEM Filed Feb. 25, 1948 IN V EN TOR.

Patented May 24, 1949 ELECTRIC REMOTE SE SYS British company LECTIVECONTROL TEM Louis Eugene Widolt Montrose-Oster, Brussels- Boitsfort,Belgium, assignor of one-half to Pollopas Patents Limited, London,England, a

Application February 25, 1948, Serial No. 10,868 In Great Britain June1, 1945 Section 1, Public Law 690, August 8, 1946 Patent expires June 1,1965 2 Claims.

This invention relates to an electric remote selective control systemwith congruently subdivided potentiometers at the transmitter and at thereceiver, the tappings of which are connected to contact paths with apreferably resilient contact arrangement, and a compensating linearranged between the tappings which comprises a switching means for acontrolling device of the driving motor at the receiver, and withshort-circuiting means for the motor armature for consuming the kineticenergy of the moving parts of the receiver, which become effective assoon as the parts of the receiver have reached one of the positionspredetermined on their contact path and respectively controlled by thetransmitter, use bein made of a plurality of different electromagneticrelays for controlling the driving motor of the receiver.

In my United States Patent No. 2,132,960, patented October 11, 1938, Ihave disclosed an electric remote selective control system of the kindabove described, wherein diiferent timing of the electromagnet relays isprovided in such a manner that, on switching off the switching means inthe compensating line, those relays which connect the driving motor tothe mains voltage in series with a resistance open only after theshortcircuiting relay of the motor armature has responded andshort-circuited the armature of the driving motor.

In the arrangement described in my prior patent there are employed sixelectromagnetic relays, one for the short-circuiting of the armature andfive for connecting the driving motor to the mains voltage, three of thelatter being employed for causing the motor to rotate in one directionand three for causing the motor to rotate in the opposite direction (onerelay bein common to both circuits).

According to my present invention the circuit of the driving motor isclosed by means of a single electromagnetic relay for each direction ofrotation.

By the operation of one electromagnetic relay the driving motor iscaused to rotate in one direction and by the operation of anotherelectromagnetic relay the drivin motor is caused to rotate in theopposite direction. Thus whereas in my prior arrangements three relaysare employed for the running of the motor in each direction and a singlerelay for the short-circuitin of the motor armature, according to thepresent invention, only three electromagnetic relays are employedinstead of the six described in my prior patent.

Preferably the circuit is so arranged that single-pole relays may beemployed.

The driving motor preferably has only one nonsubdivided field winding,and the field is strengthened simultaneously with the shortcircuitin ofthe armature.

The accompanying drawing illustrates, as an example, a diagram of thisnew circuit for the particular case of feeding with direct current. Itis shown in detail in order to make the invention particularly clear.

Referring to the drawing, I and I denote two identical potentiometers,one of which is installed at the transmitter A and the other at thereceiver B. Each potentiometer is sub-divided into a number of steps ato z and a to 2" respectively, which are connected to a contact path 2and 2 respectively arranged at A and B. The lever 3 can slide on thecontact path arranged at A and the lever 3 on the contact path at B.Through these levers, the voltage derived is transmitted to the innerrings 6 and 4' respectively. The arrangement I to therefore representsthe transmitter and the arrangement I to 4' the receiver.

While the lever 3 can be adjusted, e. g, by hand, at will to one of thecontacts a to i of the path 2, the contact lever 3' of the contact path2' is moved, for instance, through a worm wheel 5 and a worm 6 from anelectric motor, the armature and field winding of which are denoted by 1and 8 respectively. A series-wound motor has been chosen for theexample.

Parallel to the field Winding 8 are connected two resistances in series,3! and 32. Their central point is connected in series with a resistance9 and by a lead 2K! to the positive pole of the mains supply. Parallelto the armature are connected a resistance 26 and the contact of a relayH by means of the leads 27, 28 and 29. From the leads 28 and 29 a leadat carries the current to the negative pole. Parallel to the fieldwinding 8 and the resistances 3i and 32 are connected the contacts ofthe relays i2 and 13 in series, and parallel to each pair of theircontacts are condensers 33 and 34. The bridge between these two relaysi2 and I3 is connected to the lead 21 by means of a lead 24.

In the compensating line i6 between the con-- tact path 4 of the movablecontact 3 or the trans mitter and the contact path 4 of the movablecontact 3 of the receiver, a polarised changeover relay ll of well-knowntype is provided which makes contact by its movable tongue it either at18 or [9, according to the direction of the current flowing in thecompensating line IS. The circuit connection of the three relays H, l2and I3 is provided in the. following manner: The current flowing fromthe positive conductor through the lead 20 is divided at 23, passesthrough the parallel coils of the relays l2 and i3 and the parallelresistances 22 and 25 and rejoins at 2i. The whole current passesthrough the coil of relay H and reaches the negative conductor by meansof leads 29 and 30. The outer extremities of the resistances 22 and 25are connected to the contacts [8 and [9 of the polarised changeoverrelay ll, the movable tongue of which is connected to the negativeconductor by leads 29 and 30.

In the condition shown (condition of rest), therefore, only the relay Hhas attracted its armature, whereby the armature i of the control motoris short-circuited. No current flows in the connecting line l6 betweenthe members l and #3, since they are connected through the contactlevers 3 and 3' to the equipotential points g and g of thepotentiometersI and I. If the lever 3 is displaced, for instance, on to the contact 0,a potential gradient immediately arises from g to c, that is, at theterminals of the polarised relay H a voltage arises which causes thisrelay to make contact, e. g., at 18. Thereby the coil of the relay fland the series resistance 22 are short-circuited, so that the mainsvoltage now flows from the positive conductorthrough the supply lead 20,the junction 23, the coil of relay 12, the contact l8,.the movabletongue H, the leads 29 and 3.0 to the negative conductor. The currenthas now increased to such an extent that the relay l2 attracts itsarmature. Therefore at the moment when the polarized relay hasestablished contact at l'8, the relay l2 closes the circuit of thecontrol motor before the short-circuiting of the armature 1 of thecontrol motor is removed by the dropping-off of the armature of theshort-circuiting. relay H. A current now flows from the positiveconductor through the lead 25, the resistance 9 and. divides in twoparallel, unequal branches, one of which consists of the resistance 3 Iand the field winding 8, the other of the resistance 32, the currentflowing through the field coil' 8. in the direction shown by the arrow.The current passes through the closed contacts of relay l2 and the lead2 1 to the lead H, where it divides once more in two parallel branches,one being the motor armature I, the other the parallel resistance 26,and rejoins in the lead 29 and flows through the lead 30 to the negativeconductor. The motor starts running, for instance, in the direction ofthe arrow. In this case, itmoves the lever 3" downwards through the gear5, 6 until this lever has reached the contact At this moment, the motorinstantaneously stops. 0 and c repre sent equipotential points, that is,the compensating current in the line l6 ceases to flow, the polarisedrelay I! breaks the contact at l8, and before the relay l2 drops itsarmature, the difierently timed relay 1 I has already attracted itsarmature and short-circuited the armature i of the motor. Thereby, themotor instantaneously stops, since this short-circuit has taken placenot only with a normally excited field, but even with an over-excitedfield. By the short-circuiting of the armature 1, the resistance of themotor circuit has been reduced, which results in a correspondinglygreater current intensity in the motor circuit and, therefore, in thefield winding t.

Experiments have shown that the control motor in this circuit stops deadin a fraction of a revof4 lution, even if its normal speed is above 1000revolutions.

The lever 3 also follows the lever 3 in the same way if the latter isdisplaced upwards. In this case, the current in the connecting line isflows from 4 to 4', the polarised relay ll responding in such a mannerthat contact is established at 19. Thereby, the short-circuiting relay Hopens, as before, the bridge across the control motor armature '1.However, since the series resistance 25 is bridged-over this time, therelay [3 responds in attracting its armature, that is, the current inthe field winding 8 flows this time in the opposite direction to thatindicated by the arrow, so that the servo-motor runs in the oppositedirection to its previous direction, that is, against the direction ofthe arrow, whereby the contact lever 3 is moved upwards.

It is thus possible from the station A to allow the switching lever 3'at the station B to assume at will a considerable number of difierentpositions, provided that a corresponding equal number of positions and,therefore, tappings of the potentiometer is also provided at A. If thecontrol relays are constructed in the manner indicated, not only analmost simultaneous movement of the levers 3 and 3 takes place, but itis also positively ensured that the lever 3" of the receiver will stopwith almost mathematical accuracy at the predetermined position. Anyinaccuracy in the adjustment of the contact lever 3 at the receiver end,i. e., the controlled post, is therefore removed in a simple manner bythe employment of a normal motor and only three relays. Thissimplification is very important when the system is applied tocontrolling a number of posts from one. control post.

It will be observed that the motor runs in both directions by means oftwo single-pole relays only, whereas normally direct-current motors,whether shunt or series wound, and even each alternating currentcommutator motor, require at least one bi-polar changeover switch ifthey have to run in both directions. By the arrangement according tothis invention the same result is. obtained with two single-pole relaysonly, corresponding to one single-pole changeover switch.

Instead of the selector lever 3, any other wellknown selectorarrangement, for instance, With contact buttons or plugs, slide-rails,rollers,

drums or the like, may be employed. It is only necessary that thevoltage division at the trans mitter corresponds to that at thereceiver.

Instead of the contact paths with a certain number of steps it isequally possible to employ other known contact systems without steps,giving a nearly infinitely variable control.

The drawing illustrates, for better unclerstanding only the simplestconstruction of the potentiometers and contact paths. Of course, it is,advisable to choose contact paths with resilient contact movements.

I claim:

1. An electric remote selective control system comprising twoelectrically similar potentiometers with movable selectors positioned atthe controlling and controlled ends respectively of the system, acontrol motor having a field winding and an armature, for controllingthe movement of the selector of the potentiometer at the controlled endof the system, a circuit for said motor including two resistances inseries, of which one resistance is connected in parallel with said fieldwinding and has a midpoint connection to one pole of a current supplysource, and the other resistance is connected in parallel with saidarmature and is connected at one end to the other pole of said source,two single-pole relays each for controlling the opening and closing ofboth the field and armature circuits of said motor, one of said relayshaving an off position and a circuit-closing position connecting theother end of said second-mentioned resistance to one end of saidfirst-mentioned resistance for causing rotation of said motor in onedirection, and the other of said relays having an off position and acircuit-closing position connecting said other end of saidsecond-mentioned resistance to the other end of said first-mentionedresistance for causing rotation of said motor in the opposite direction,and a third single-pole relay connected in parallel with said armaturefor controlling short-circuiting of said armature, a compensatingcircuit connecting said selectors of said potentiometers, saidcompensating circuit controlling all three of said relays and beingresponsive to establishment of a potential difference between saidselectors caused by movement of the selector at the controlling end ofthe system, for selectively operating one or the other of said twofirst-mentioned relays according to the direction of current flow insaid compensating circuit, whereby the field and armature circuits ofsaid motor are closed by the operative one of said two first-mentionedrelays to effect, in response to the movement of the selector at thecontrolling end of the system, a rotation of said motor and movement ofthe selector controlled thereby in the direction and to the extentnecessary to establish an equipotential condition between selectors,said third relay being timed differently from said two first-mentionedrelays whereby establishment of such equipotential condition causes saidthird relay to short-circuit said armature before the operative one ofsaid two first-mentioned relays opens the field and armature circuits tointerrupt current supply from said source to said armature, said fieldwinding and said resistances, whereby to eirect a rapid stoppage of saidmotor responsive to establishment of such equipotential condition.

2. An electric remote selective control system comprising twoelectrically similar potentiometers with movable selectors positioned atthe controlling and controlled ends respectively of the system, acontrol motor having a single nonsubdivided field winding and anarmature, for controlling the movement of the selector of thepotentiometer at the controlled end of the system, a circuit for saidmotor including two resistances in series, of which one resistance isconnected in parallel with said field winding and has a midpointconnection to one pole of a current supply source, and the otherresistance is connected in parallel with said armature and is connectedat one end to the other pole of said source, two single-pole relays eachfor controlling the openmg and closing of both the field and armaturecircuits of said motor, one of said relays having an off position and anoperative, circuit-closing position connecting the other end or" saidsecondme-ntioned resistance to one end of said firstmentioned resistancefor causing rotation of said motor in one direction, and the other ofsaid relays having an off position and an operative, circuit-closingposition connecting said other end of said second-mentioned resistanceto the other end of said first-mentioned resistance for causing rotationof said motor in the opposite direction, and a third single-pole relayconnected in parallel with said armature for controllingshort-circuiting of said armature, a compensating circuit connectingsaid selectors of said potentiometers, said compensating circuitcontrolling all three of said relays and being responsive toestablishment of a potential difference between said selectors caused bymovement of the selector at the controlling end of the system, forselectively operating one or the other of said two firstmentioned relaysaccording to the direction of current fiow in said compensating circuit,whereby the field and armature circuits of said motor are closed by theoperative one of said two firstmentioned relays to effect, in responseto the movement of the selector at the controlling end of the system, arotation of said motor and movement of the selector controlled therebyin the direction and to the extent necessary to establish anequipotential condition between said selectors, said third relay beingtimed difierently from said two first-mentioned relays wherebyestablishment of such equipotential condition causes said third relay toshort-circuit said armature before the operative one of said twofirstmentioned relays opens the field and armature circuits, whereby thekinetic energy of the moving parts of said motor is rapidly absorbed bythe short-circuiting of said armature occurring while the field circuitis still closed and the field of the motor is simultaneously reinforcedin consequence of said short-circuiting, to effect a rapid stoppage ofsaid motor responsive to establishment of such equipotential condition.

LOUIS EUGENE WIDOLT MONTROSE-OSTER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,070,647 Whittingham Aug. 19,1913 2,132,960 Montrose-Oster Oct. 11, 1938 FOREIGN PATENTS NumberCountry Date 246,328 Great Britain J an. 28, 1926

